Global benefits of the Space Enterprise Facility /SEF/ using the external tank

Based on the assumption that a manned commercial facility will evolve in the future, an external tank-derived SEF (Space Enterprise Facility), financed and constructed by government in partnership with private investors may present the fastest and most economical scenario for the development of commercial operations in space. At little additional cost and with minimal payload-offload, an orbital mission profile for the external tank (ET) would enhance Shuttle performance by allowing more residual fuel to be burned and would increase cargo capacity by 26% and habitable volume by 85%. An SEF consisting of two ETs with a free-flying pallet platform could provide goods and services producing revenues which would return the investment in 7.5-10.8 years. The total cost of such a facility for the first 10 years would be approximately $2.1 billion.